Thursday, January 24, 2013

lit: Asymmetric Drift and the Stellar Velocity ellipsoid

Asymmetric Drift and the Stellar Veloocity ellipsoid by Westfall, Bershady et al.:The shape of the stellar velocity ellipsoid, defined by \sigma_R, \sigma_{phi}, and \sigma_z, provides key insights into the dynamical state of a galactic disk: \sigm_z:\sigma_R provides a
measure of disk heating and \sigma_{phi}:\sigma_R yields a check on the validity of the epicycle
approximation (EA). Additionally, \sigma_R is a key component in measuring the
stability criterion and in correcting rotation curves for asymmetric drift (AD),
while \sigma_z is required for measuring the disk mass-to-light ratio.
See also p.2 on asymmetric drift corrections for stellar velocities.